Process for the formation of colored decorations and of printing on enamel and glazes



Patented Dec. 31, 1940 PROCESS FOR THE FORMATION OF COL- ORED DECORATIONS AND OF PRINTING N ENAMEL AND G Ernst Paul .Schlegel,

, Offenbach-on-the-Main,

Germany, assignor to Deutsche Gold and Silber Scheideanstalt Vorm'als Roessler, Frankfort-onthe-Main, Germany, a corporation of Germany No Drawing. Application February 23, 1937, Se-

rial No. 127,200. In Germany February 25,

8 Claims.

This invention relates to a process for forming colored decorations and for printing on enamels and glazes. More specifically it relates to the production of colored decorations and the formation of printing on enamels such as those used to coat iron and steel. The decoration of iron and steel enamels by a process in which the ceramic color is applied and fired on the crude unfired enamel or glaze is the' particular 10 field in which my invention has been found most useful. v Previously when decorating enamels it has been necessary first to fire the enamel on the base material to be decorated which may be an iron or steel plate or a glass object. The color is then applied tothe fired enamel, this color being usually mixed with water or with a mixture of turpentine. Finally the entirecombination was then subjected to a second firing, in order to fire the decoration or on the enamel.

This invention has for one of its objects the development of a process which makes it possible to eliminate one of these firings. Thus, it is an object of this invention to fire the crude enamel containing the color decorations or printing in a single step, thus eliminating one of the firing operations now considered necessary by the art.

The applicant has discovered, however, that with the colors now known to the industry, mixed in the usual manner with water or with similar vehicles, it has not been possibleto obtain uniformly successful results when attempting to dispense with one of the firing operations. Utilizing single stage'firing in accordance with my.

invention with colors ground with vegetable oils always resulted in colored decorations wherein bubbling or cracking of the enamel at the decorated places was observable. Colors mixed with 40 water on the other hand, always formed enamels containing so-called water streaks, resulting from bleeding of the color.

In an efiort to develop a Vehicle which would permit the obtainment of completely satisfactory decorations or printing, of distinct deep shades and sharp outline, on crude enamels in a single firing, I have observed that the mineral oils or oils resulting from the distillation of coal are most effective as media for the color. For example, I have found that a mixture of a mineral oil of low viscosity, such as a low viscosity petroleum oil, and a mineral oil of high viscosity, such as lubricating oil, is very effective when utilized as a vehicle for the color. The relative 65 amounts of the highly viscous oil and of the oil printing in place I of lower viscosity areproportioned in the same manner as is now customary when using heavy oil (prepared by oxidation of oil of turpentine) or turpentine oil mixtures. The relative amounts of highly viscous and less viscous oilslhave been found to depend'on the color used and on the manner of application of the color to the enamel.

The addition of a few percent (based on the oil mixture) of lubricating oil to the slightly viscous oil is generally suificient to produce a color which is suitably impregnated with the binding agent and is of a consistency suitable for application. I have found it possible to utilize benzene or any other oil derived from coal tar in place of a mineral oil. For carrying out my process I prefer to utilize non-poisonous lead-free colors which yield decorations in which the color is of greater fastness than ordinarily obtained with the lead-containing colors.

The color can be applied to the crude enamel to be decorated by any of the known methods, such as by painting, spraying, edging, bordering, or stenciling. Injury to the crude enamel may be easily avoided without difficulty when applying the color. However, when. the color is sprayed, I prefer to use-a slightly viscous oil mixture and to spray the color with care in order to avoid injury to the crude enamel. Stenciling methods, especially those utilizing thin stencils, for example stencils of tin foil, as now used in the white ware industry but not in the enamel industry, have been found to yield especially successful results. In stenciling methods the bottom of the stencil is preferably covered with an oil repelling agent in order to prevent the stencil from adhering to the crude enamel.

. My novel colors suspended in novel vehicles yield especially improved results in the decoration of iron or steel enamels in accordance with the process herein set forth. The preparation of printed enamel signs, such as sheet enamel sign plates, is very much simplified by the elimination of one of the firing operations. The cost of producing these signs is also considerably reduced for these articles can now be made continuously and by mass production methods. .Certain enameled objects, as, for example, gauge and measuring vessels, have been frequently supplied with an inscription or a scale. Upuntil the present time such articles have usually been subjected to a second firing in order to obtain satisfactory printing of the inscription or scale. The increased cost as well as the danger of injury to the enamel due to the detrimental stresses set up in the article and enamel during the second firing operation are eliminated in the method forming the subject matter of this aputilizingmy novel vehicles for the colors accord--.

ing to the process forming the subject matter of this application, the second firing can now be eliminated. My process is therefore also useful for the decoration of ceramic glazes in a processinvolving but a single firingoperation.

Example A ceramic color was ground with a mixture of petroleum and lubricating oil and painted on a crude unfired enamel. The enamel and decoration were both then fired in a single firing operation. The resulting decorated enamel was entirely satisfactory.

In the appended claims the word enamel, wherever used, is intended to cover enamels of all types, such as those suitable for application toiron and steel, glass enamels, and low melting glazes. The operation of grinding the ceramic color with a vehicle, wherever specified, is intended tocover suspension of the color in the vehicle by any means or method equivalent to grinding. By a. crude unfired enamel is meant one wherein the enamel or glaze composition is applied to the article to be decorated and not subjected to the usual preliminary firing before application of the ceramic color to the enamel. This explanation is made in order to avoid the use oi. unnecessary verbiage in the claims in describing the invention.

Since it is obvious that various changes and modifications may be made in the foregoing description without departing from the nature or spirit thereof, my invention is not to be restricted except as necessitated by the appended claims.

I claim:

1. A process for the preparation of colored decorations and printing on enamels and glazes which consists in grinding a ceramic color with an oil, applying the resulting color suspended in an oil medium to the unfired enamel or glaze layer, and then firing said crude enamel and color together in a single firing operation.

2. A process for the preparation or colored decorations and printing on enamels and glazes which consists in grinding a ceramic color with a mineral oil, applying the resulting color suspended in an'oil medium to the unfired enamel layer, and then firing together crude enamel and color in a single firing operation.

3. A process for the preparation of colored decorations and printing on enamels and glazes which consists in grinding a ceramic color with a coal tar distillation oil, applying the resulting color suspended in an oil medium to the unfired enamel layer to be decorated, and then firing together crude enamel and decoration in a single firing operation.

4. A process for the preparation of colored decorations and printing on enamels and glazes which consists in grinding a ceramic color with a mixture of petroleum and lubricating oils, applying the resulting color suspended in an oil medium to the unfired enamel layer to be decorated, and then firing together crude enamel and color in a single firing operation.

5. A process for preparing colored decorations and printing on enamels and glazes which consists in grinding a ceramic color with an oil, applying the resulting color suspended in an oil vehicle to the crude unfired enamel to be decorated through a stencil, and then firing together crude enamel and color in a single firing operation.

6. A process for preparing colored decorations and printing on enamels and glazes which con sists in grinding a lead-free ceramic color with an oil, applying the resulting color suspended in an oil vehicle to a. crude unfired enamel to be decorated, and then firing together crude enamel and color in a single firing operation.

7. A process for preparing colored decorations and printing on enamels and glazes which consists in grinding a lead-free ceramic color with a mixture of petroleum oil and a lubricating oil, applying the resulting color suspended in an oil vehicle to the crude unfired enamel to be decorated, and then firing together crude enamel and color in a single firing operation.

8. A process for preparing colored decorations and printing on enamels and glazes which consists in grinding a lead-free ceramic color with an oil, applying the resulting color suspended in an oil vehicle to the crude unfired enamel to be decorated through a stencil, and then firing together crude enamel and color in a single firing operation.

' ERNST PAUL SCHLEGEL. 

